Industrial processes often rely on energy sources such as combustion to generate steam or as heat for a feedstock liquid. Some combustion processes involve operation of a furnace or boiler. While combustion provides a relatively low cost energy source, combustion efficiency is often sought to be maximized within a process, because the resulting flue gases exiting the system may be subject to regulations regarding emissions of harmful gases. Accordingly, one goal of the combustion process management industry is to maximize combustion efficiency of existing furnaces and boilers, which inherently reduces the production of greenhouse gases or other harmful byproducts. Combustion efficiency can be optimized by maintaining the ideal level of oxygen in the exhaust or flue gases coming from a combustion process which ensures oxidation of combustion byproducts.
In situ or in-process analyzers are commonly used in monitoring, optimizing, and/or controlling an on-going combustion process. Typically, such analyzers employ sensors configured to be heated to, and withstand, relatively high temperatures, and to operate directly above, or near, the furnace or boiler combustion zone. Known process combustion analyzers typically employ a zirconia oxide sensor disposed at one end of a probe that is inserted directly into a flue gas stream. As the exhaust or flue gas flows into the sensor, it diffuses through a filter, often called a diffuser, into proximity with the sensor. There are no pumps or other flow inducing devices used to direct a sample flow into the sensor, instead, the gas is diffused passively through the diffuser filter. The sensor provides an electrical signal related to the amount of oxygen present in the gas. While the diffuser allows diffusion therethrough, it also protects the sensor from physical contact with airborne solids or particulates.